This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. xc2xa7 119 from my application OPTICAL PICKUP ASSEMBLY CAPABLE OF ADJUSTING INCLINATION filed with the Korean Industrial Property Office on Jun. 9,1998 and there duly assigned Ser. No. 21324/1998.
1. Field of the Invention
The present invention relates to an optical pickup assembly which can adjust the relative inclination between an objective lens and a disk to prevent the deterioration of recording or reproduction signals due to a warped state or inclination of the disk.
2. Description of the Related Art
In general, an optical pickup records or reproduces information while moving across a recording medium such as a disk. The optical pickup includes an objective lens which focuses light emitted from a light source and forms an optical spot on the disk. The objective lens is installed at an actuator capable of moving the objective lens in a radial and focus direction of the disk such that the optical spot can be formed on a correct position on a track of the disk.
However, when the disk is in a warped state or inclined with respect to the objective lens, the recording or reproduction of signals is deteriorated. To prevent such deterioration, an inclination adjustment apparatus for an optical pickup has been suggested
In such an apparatus, an optical pickup is hinge-coupled by a support member to a rack gear member. The rack gear member is moved across a disk in response to the drive of a driving motor. An inclination adjuster for supporting the optical pickup and adjusting the inclination thereof is provided at one end of the rack gear member. A tilt detector for detecting the inclination of the disk with respect to the optical axis of an objective lens is provided on the upper surface of the optical pickup. The optical pickup includes an actuator having a focusing and tracking coil for driving the objective lens.
The inclination adjuster includes a motor and an elevating portion for moving one end of the optical pickup up and down according to the rotation of the motor so that the inclination of the optical pickup is adjusted via a hinge shaft.
The tilt detector includes a light source radiating light to the disk at a predetermined angle, first and second photodetectors installed symmetrically at either side of the light source and receiving the light reflected by the disk, and a differential amplifier outputting a signal proportional to the difference between the signals detected by the first and second photodetectors.
Thus, since the detection signals of the first and second photodetectors vary according to the degree of inclination of the disk, the inclination of the optical pickup can be adjusted by feeding back the signal output from the differential amplifier to the inclination adjuster.
However, because additional elements such as the motor are required in the above apparatus to adjust the inclination of the optical pickup, the overall size of the apparatus becomes large and the structure thereof becomes complicated. Also, because the optical pickup which is large in volume and weight is subject to the adjustment, a large driving power is needed for the motor and the speed of adjustment becomes slow. Thus, the apparatus is not suitable for high speed recording or reproduction.
To solve the above problems, it is an object of the present invention to provide an optical pickup assembly having a magnetic circuit so that the relative inclination between an objective lens and a disk can be adjusted.
Accordingly, to achieve the above object, there is provided an optical pickup assembly which includes a base, a bobbin having an objective lens mounted thereon, the bobbin being installed at the base so as to be movable and having a pair of first side surfaces parallel to a radial direction of a disk and a pair of second side surfaces parallel to the tangential direction of a disk track, a focus coil wound around the bobbin for driving the objective lens in a focus direction, a track coil installed at the first side surfaces for driving the objective lens in a radial direction of the disk, a driving magnet installed at the base to face the first side surfaces, a tilt coil installed at the second side surfaces for driving the objective lens in response to the relative inclination between the objective lens and the disk, a first tilt magnet installed at the base such that one polarity thereof faces the tilt coil, a second tilt magnet installed at an upper portion of the first tilt magnet such that another polarity opposite from the. one polarity thereof faces the tilt coil, an inclination detector for detecting the relative inclination between the objective lens and the disk, and a cover coupled to the base to protect the objective lens.
According to another aspect of the present invention, there is provided an optical pickup assembly which includes a base, a bobbin having an objective lens mounted thereon, the bobbin being installed at the base so as to be movable, a focus coil wound around the bobbin for driving the objective lens in a focus direction, a track coil installed at a side surface of the bobbin for driving the objective lens in a radial direction of the disk, a driving magnet installed at the base such that one polarity thereof faces the focus coil and the track coil, a pair of tilt coils, installed such that they are spaced a predetermined distance from at least one side surface of the bobbin where the track coil is attached, for driving the objective lens in response to the relative inclination between the objective lens and the disk, a pair of tilt magnets, installed at a lower portion of the driving magnet such that a polarity opposite to the polarity of the driving magnet faces each of the tilt coils, an inclination detector for measuring the relative inclination between the objective lens and the disk, and a cover coupled to the base to protect the objective lens.